Anais da Academia Brasileira de Ciências (2015) 87(2): 985-996 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 http://dx.doi.org/10.1590/0001-3765201520140475 www.scielo.br/aabc Growth of the tropical zoanthid Palythoa caribaeorum (Cnidaria: Anthozoa) on reefs in northeastern Brazil JANINE F. SILVA1, PAULA B. GOMES2, ERIKA C. SANTANA2, JOÃO M. SILVA2, ÉRICA P. LIMA3, ANDRE M.M. SANTOS3 and CARLOS D. PÉREZ3 1Pós-Graduação em Biologia Animal, Universidade Federal de Pernambuco, Rua Prof. Moraes Rego, 1235, Cidade Universitária, 50670-420 Recife, PE, Brasil 2Universidade Federal Rural de Pernambuco, Departamento de Biologia, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, 52171-900 Recife, PE, Brasil 3Universidade Federal de Pernambuco, Centro Acadêmico de Vitória, Núcleo de Biologia, Rua do Alto do Reservatório, s/n, Bela Vista, 55608-680 Vitória de Santo Antão, PE, Brasil Manuscript received on September 16, 2014; accepted for publication on November 28, 2014 ABSTRACT In Brazilian reefs, zoanthids, especially Palythoa caribaeorum are fundamental for structuring the local benthic community. The objective of this study was to determine the growth rate of P. caribaeorum, and to assess the influence of the site (different beaches), season (dry and wet), location (intertidal or infralittoral zones), and human pressure associated with tourism. For one year we monitored the cover of P. caribaeorum in transects and focused on 20 colonies. We cut off a square (100 cm2) from the central part of the colony and monitored the bare area for four months in each season. The average growth rates varied from 0.015 and 0.021 cm.day-1. The rate was homogeneous in all localities, and there was no influence from colony site, location, or touristic visitation, showing that the growth velocity may be an intrinsic characteristic of the species, with a strong genetic component. The growth rate of P. caribaeorum differed among months, and peaked in the first month after injury. The average cover varied from 6.2 to 22.9% and was lower on the reef visited by tourists. The present study corroborates the hypothesis that P. caribaeorum is important for coastal reef dynamics due to its fast and continuous growth. Key words: growth rate, trampling, tropical reefs, zoantharia. INTRODUCTION 0.5% of sea bottoms (Moberg and Folke 1999), Coral reefs are very important due to the biological interactions, in particular competition, several ecosystem services they provide (Dight and are essential to maintain the dynamics and the Scherl 1997, Moberg and Folke 1999), their high diversity of their community. productivity (Connell 1978, Birkeland 1997), their Among the biological groups that best biodiversity (Moberg and Folke 1999), and their characterize reefs in the world are anthozoan dynamism (Osborne 2000). As they occupy only cnidarians. The species composition of this group varies geographically, but dominant species play Correspondence to: Carlos Daniel Pérez E-mail: [email protected] similar ecological roles in different reefs. This is An Acad Bras Cienc (2015) 87 (2) 986 JANINE F. SILVA et al. the case of scleractinian corals and zoanthid (Fautin colony fission (McFadden 1986), which contributes 1988). Both are sessile, suspensivorous, mostly to population size, from the fission of an individual carnivorous, can bear zooxanthellae in their tissues, polyp, which contributes to colony growth (Acosta and play a key role in community structuring. et al. 2005). In this context, the influence of the Zoanthids form dominant groups of sessile environment on the colony’s growth rate for P. macroinvertebrates in reefs, such as those in Jamaica caribaeorum (and zoanthids in general) is still (Karlson 1980), whereas scleractinians predominate poorly known. in reefs in the Indo-Pacific (Fautin 1988). In Considering the high ecological importance of addition, zoanthids may dominate sites where stress this species in Brazilian reefs and its competitive conditions lead to a decrease in scleractinian corals interactions, the objectives of the present study (Fautin 1988), such as Hawaii (Cooke 1976) and were to estimate the growth rate of P. caribaeorum Brazil (Cruz et al. in press). Brazilian coastal reefs in reefs in the northeastern coast of Brazil and are covered mainly by zoanthids (Oigman-Pszczol to test whether this rate changes under different et al. 2004, Floeter et al. 2007, Francini-Filho et al. environmental conditions. The results will allow us 2013) and the dominant species is P. caribaeorum, to understand the role of this species in structuring which is common in the western Atlantic (Acosta et benthic community. al. 2005, Francini-Filho et al. 2013). MATERIALS AND METHODS The broad distribution and high cover of P. caribaeorum is probably the result of several STUDY AREA factors, such as colony plasticity (Karlson 1983, We carried out the present study in the tropical Costa et al. 2011), physiological tolerance (Sebens reefs at Porto de Galinhas (8°33’ 00’’- 8°33’33” S; 1982), mixture of sexual and asexual reproductive 35°00’27’’- 34°59’ 00’’ W) and Suape (8°21’ 45”- strategies (Fadlallah et al. 1984, Acosta and Asbahr 8°23’27’’ S; 34°56’ 44’’ - 34°57’30’’ W) beaches 2000, Acosta et al. 2001), fast growth (Suchanek and in the State of Pernambuco in northeastern Brazil Green 1981, Rabelo et al. 2013), strong competitive (Fig. 1). The area has a warm and humid climate. ability (Bastidas and Bone 1996), and anti- Historical average annual rainfall is 2,483.6 mm and predator mechanisms (Sebens 1982). In addition, average annual temperature is 24.7°C. There is little P. caribaeorum produces palytoxin (Tubaro et al. temperature variation throughout the year (from 26 2011), which together with the factors mentioned to 30°C), but there is a strong difference in rainfall above, makes this species an aggressive competitor distribution. The rainy season (March to August) for space in reefs (Suchanek and Green 1981, Acosta concentrates over 70% of the annual rainfall. Hence, et al. 2001, Mendonça-Neto and Gama 2009). the region is characterized by two climatic seasons: The capacity of reproduction, survival, and dry and rainy (Medeiros et al. 1999). substrate cover is directly related to the size of The beaches have fringe reef formations, benthic organism colonies (Jackson 1977, Hughes known as sandstone banks or beachrocks (Laborel and Cancino 1985, Garrabou 1999, Acosta et al. 1970). Suape, located 40 km away from Porto de 2001, 2005). In P. caribaeorum the process of colony Galinhas, has a reef line with 3,500 m in length and fission has been well studied, as well as the action 80 m in width, at approximately 1,200 m from the of environmental conditions on polyp morphology, coastline making the access of people to the reef fission and fragmentation rates (Acosta et al. 1998, difficult. Conversely, the reef of Porto de Galinhas 2001, 2005, Acosta and Sammarco 2000, Costa et has an extension of 900 m and is close to the beach al. 2011). However, it is important to differentiate line, within easy access, which makes this beach one An Acad Bras Cienc (2015) 87 (2) GROWTH OF Palythoa caribaeorum IN BRAZILIAN REEFS 987 Figure 1 - Location of the Suape and Porto de Galinhas beaches along the coast of the State of Pernambuco, in northeastern Brazil. of the most visited in the Brazilian coast. Annually, which would be observed close to the free edge of Porto de Galinhas receives approximately 65,000 the colony. During the entire experiment the site tourists (Sarmento et al. 2011). The reef is divided was not occupied by other organisms, and, hence, in two sectors by a channel with approximately 8 m scraping or removal was not necessary. in depth. The south sector consists of an area The center of the square formed by tissue delimited by buoys that allow visits by tourists to removal was marked with underwater epoxy resin specific parts of the reef (visited reef). The north (TECPOX MES-500) to facilitate its location (Fig. 2). sector does not receive tourists, mainly due to the Each colony was marked with a PVC plate attached lack of natural pools and the strong irregularity of to the reef and its location was marked with a the reef (unvisited reef). To characterize the areas GPS. Digital images of the square area were taken with and without tourists, on a Saturday in May, monthly with a Canon Power Shot A620 camera two independent observers counted the reef walkers and then analyzed in the program IMAGE J 1.6.0 during four periods of 10-min of observations with to measure the area without zoanthid cover and 20-min intervals between them. its perimeter. To assess the influence of seasonality on the SAMPLING DESIGN growth of P. caribaeorum, we removed an area of In order to estimate the growth rate of P. caribaeorum, the colony in the dry season and monitored it during we monitored 20 colonies picked at random. It was four months (December 2010 to March 2011). We removed a 100 cm2 square of the central region repeated the same procedure with other colonies of the colony with a spatula. The objective of this starting in the rainy season and also monitored experiment was to find the maximum growth rate of them during four months (May to August 2011). the colony without the interference of competitors, The experiments were carried out simultaneously An Acad Bras Cienc (2015) 87 (2) 988 JANINE F. SILVA et al. Figure 2 - Colony of Palythoa caribaeorum with an experimental area on the first day of experiment. The center of the square (100cm2) formed by tissue removal was marked with underwater epoxy resin to facilitate its location. on the beaches Porto de Galinhas (unvisited reef) In addition, the initial bare area may vary little and Suape, aiming at estimating the average growth among colonies, and the growth rate should be rate of P.